At present, various optical recording media such as CD-R/RW, DVD±R/RW and MO, are widely accepted and used as external storage devices for information processing systems such as computers, since they can store information of a large capacity and whereby random access is easy. Among them, an organic dye type optical recording medium represented by CD-R or DVD-R is considered to have superiority in that it is less costly and easy to produce.
Further, as the volume of information to be processed has increased, it is desired to increase the recording density of a medium. In recent years, an optical recording medium capable of high density recording and reading has been recommended which employs a laser having a short oscillation wavelength (so-called short wavelength laser) such as a blue laser, which has been actively developed (e.g. JP-A-2000-043423).
Usually, in the case of an optical recording medium commercially available as CD-R or DVD-R, for example, CD-R is designed to be suitable for recording or reading by a laser beam having a wavelength of about 780 nm, and DVD-R is designed to be suitable for recording or reading by a laser beam having a wavelength of from about 600 to 700 nm. Such a recording medium which is suitable for optical recording or reading by means of a laser beam having a relatively long wavelength, has a problem that if recording or reading is carried out by means of a laser of a shorter wavelength, the reflectance is so low that it is impossible to carry out recording or reading. Here, the blue laser is usually meant for a laser having a wavelength of from about 350 nm to 530 nm.